what is cancer ?
Cancer is a term representing abnormal cell growth, which may be benign or malignant. A neoplasm or tumor is a mass of tissue showing abnormal uncontrolled proliferation of cells. Cancer is the second most cause of death after coronary artery disease in the world. Out of which the most common cancer are lung, skin, bowel, and breast. The etiology of cancer mostly includes cigarette smoking, diet, oncogenes, hereditary and geographical distribution. Oncogene is a concept where cancer occurs by depression of viral oncogenes to its malignant form.
Pathophysiology of cancer cell results due to mutation , cell adopts characteristics which leads to increase growth or decreased apoptosis. cell can be divided into two types:
1. Benign: These are cells which are alike normal cell but show uncantrolled cell proliferation.
2. Malignant: Does not have ability to show proliferation.
Mutation of cell inactivates tumor suppressor gene( Tumor suppressor genes are normal genes that slow down cell division, repair DNA and gives cell signals when to die ( apoptosis). Incordination in tumor supresssor genes leads to cell growth in uncontrollable manner causing cancer. Mutation also inactivates DNA repair gene and proto-oncogenes which leads to formation of oncogene which in turn leads to cancer.
Cancer cell has the ability to spread in all parts of the body.
- Carcinoma begins from skin and tissue which lines the internal organs.
- Sarcoma begins from bone, fat muscles and cartilage.
- Leukemia starts from bone marrow and enters the blood stream.
- Lymphoma and myeloma begin proliferating from immune system.
- Malignancy are cancer of central nervous system which begins from brain and spinal cord.
Tumors are the mass of tissue which is formed from the abnormal cell proliferation. tumors contains 2 components: Parenchyma which determines nature and evolution of tumor and supportive stroma determines which parenchymal tumor cell will grow. The naming based on the cell are as melanoma for melanocytes, lymphoma for lymphoid tissue, hepatoma for hepatocytes, and seminoma for testis.